X-ray Photoelectron Spectra of Poly(2-vinylpyridine) and its Adduct with Boron Trifluoride

The sources of interactions at an interface and in solution have been subjects which have occupied both experimentalists and theorists for some time. Several types of interactions, e.g. donor-acceptor,^1–6 have been suggested to explain deviations in adhesion and solution data from that predicted from London dispersion forces. The experimentalist has employed both infrared spectroscopy and calorimetry to measure donor-acceptor interactions. It is the purpose of this note to show that X-ray photoelectron spectroscopy (XPS) can be used also to detect donor-acceptor interactions in polymeric systems.     

A Preliminary Study of the Use of Kynar® Piezoelectric Film to Measure Peel Stresses in Adhesive Joints

A variety of test techniques have been developed to test the performance of adhesives bonded in situ within joints. Most of these techniques measure strength, fracture toughness, or adhesive modulus of the bonded joint. Techniques to measure actual stress or strain values within a bonded joint are quite few in number. The Krieger gage¹ is able to measure the average shear displacement along a 12.5 mm. gage length of a thick adherend joint. It has been used primarily to measure in situ shear moduli of adhesives. Brinson and his colleagues² proposed bonding strain gages within adhesive joints to measure strains within the adhesive. Unfortunately, these gages are only sensitive to the lateral strains and not shear or peel strains. Because the lateral strains are dominated by the behavior of the adherends rather than the adhesive, the information which can be gained is incomplete.     

Carbon dioxide separation and dry reforming of methane for synthesis of syngas by a dual‐phase membrane reactor

High‐temperature CO₂ selective membranes offer potential for use to separate flue gas and produce a warm, pure CO₂ stream as a chemical feedstock. The coupling of separation of CO₂ by a ceramic–carbonate dual‐phase membrane with dry reforming of CH₄ to produce syngas is reported. CO₂ permeation and the dry reforming reaction performance of the membrane reactor were experimentally studied with a CO₂–N₂ mixture as the feed and CH₄ as the sweep gas passing through either an empty permeation chamber or one that was packed with a solid catalyst. CO₂ permeation flux through the membrane matches the rate of dry reforming of methane using a 10% Ni/γ‐alumina catalyst at temperatures above 750°C. At 850°C under the reaction conditions, the membrane reactor gives a CO₂ permeation flux of 0.17 mL min^?1 cm^?2, hydrogen production rate of 0.3 mL min^?1 cm^?2 with a H₂ to CO formation ratio of about 1, and conversion of CO₂ and CH₄, respectively, of 88.5 and 8.1%. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2207–2218, 2013     

Bio‐Chemimechanical Pulps from Eucalyptus grandis: Strength Properties,Bleaching, and Brightness Stability

Abstract

Eucalyptus grandis wood chips were treated with the white‐rot fungus Ceriporiopsis subvermispora in a 100‐L bioreactor for 15 days. The treatment was characteristic of a selective biodelignification (7.6±0.2% and 0.3±0.2% of lignin and glucan losses, respectively) with concomitant extractive removal (17.7±0.2%). Biotreated samples and non‐inoculated controls were pre‐cooked in alkaline sulfite and post‐refined in a Jokro mill. The biotreated pulps fibrillated more rapidly and contained lower amounts of rejects than the control. To achieve a freeness of 400 mL, the control pulp required 125 min of beating, whereas the biopulp required only 95 min, a reduction of 24%. Unbleached biopulps had better strength properties than control pulps because higher tensile indexes were obtained for the entire range of tear indexes. Bleaching with 8% hydrogen peroxide increased the brightness of these pulps by 17 points. At low peroxide loads, the brightness increase for biopulps was lower than for the control pulps. Still, the bleachability of sboth pulps was similar for peroxide loads higher than 2%. After a two‐stage H₂O₂‐bleaching sequence, final brightnesses for the control and biopulps were 59.7±0.8% and 60.5±0.4%, respectively. Brightness stability of the bleached control and bio‐CMP pulps to photo and thermal aging were very similar.     

Processing of Composite Thin Film Solid Oxide Fuel Cell Structures

A solid oxide fuel cell (SOFC) structure is proposed in which a composite thin film cathode substrate supports a dense thin film electrolyte with a thickness of less than 1 μm. The cathode substrate has a graded porosity achieved through the partial sintering of a spin-coated CeO₂ colloidal suspension. The resulting surface has a pore size and surface roughness which allowed a fully dense ZrO₂:16%Y (YSZ) electrolyte to be spin-coated directly from a polymeric precursor without capillary forces removing the precursor from the surface of the porous substrate. Using this process, fuel cell structures were constructed with temperatures not exceeding 800°C. The porous CeO₂ interlayer should allow for decreased ohmic losses, as well as decreased reactions between the YSZ and the cathode substrate. In addition, the nanocrystalline grain sizes should allow for increased catalytic activity on the cathode. Calculated ohmic losses indicated the resistance of the CeO₂ interlayer limited the power of the structure, which was minimized by impregnating the porous layer with a mixed-conducting perovskite. The final structure shows significantly reduced ohmic losses as calculated at 400°C.     

High-Toughness Silicon Carbide as Armor

Silicon carbide, with single-edge precracked beam (SEPB) toughness greater than 7 MPa·m^1/2, was made by hot-pressing using Al–B–C (ABC) or Al–Y₂O₃ (YAG) as additives. The hardness of SiC processed with a liquid phase was always less than SiC densified without a liquid phase despite having a similar or finer grain size. With increasing Al content, the ABC system changed from trans- to intergranular fracture with a drop in hardness and a two- to threefold increase in SEPB toughness. Strength and Weibull modulus for materials processed with a liquid phase were higher than those of solid-state densified SiC. Ballistic testing, however, did not show any improvement over SiC densified with B and C additives. Depth of penetration was controlled by hardness of the SiC-based materials, while V ₅₀ values for 14.5 mm WC–Co cored projectiles were in the range of 720–750 m/s for all materials tested.     

Parameter Estimation for Periodically Stationary Time Series

Abstract. The innovations algorithm can be used to obtain parameter estimates for periodically stationary time series models. In this paper, we compute the asymptotic distribution for these estimates in the case, where the innovations have a finite fourth moment. These asymptotic results are useful to determine which model parameters are significant. In the process, we also develop asymptotics for the Yule–Walker estimates.     

包含需求侧管理的输配电系统优化运行──模型及应用研究

研究了包含蓄热（冷）技术装置、负荷（商业集中式空调负荷等）直接控制（音频、无线电等）技术以及分时（峰谷）电价结构等需求侧管理措施的输配电系统优化运行（调度）的多目标规划模型，并应用模型及软件（整体资源计划软件，ＩＲＰ－ＣＳ，ＣＯＲＥ版权）进行了实例分析，给出了结果。     

Development of an evanescent wave fiber optic biosensor

Biosensors are uniquely qualified to meet the need for rapid, inexpensive analytical procedures. The authors' intent was to develop a simple, real-time immunoassay that could process multiple samples in a semi-automated manner, while maintaining maximum versatility to permit its application under various conditions. To achieve this goal, the authors have developed a biosensor which detects antibody-antigen binding within the evanescent wave of an optical biosensor